JPH10224125A - 90× hybrid circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a circuit and to reduce a manufacturing cost by connecting prescribed capacity of capacitance between the middle point of a distribution constant line and a GND. SOLUTION: At the time of setting the lengths of transmission lines 5 and 6 to be a length equivalent to an arbitrary phase angle θ1 (0<θ1 <=90 deg.) at a using frequency, as the distribution constant line impedance Z1 =Z0 /2<1/2> .tan(θ1 /2) is made, the capacitances 9 and 10 of a capacitor C1 =2<1/2> .(1/cos<2> (θ1 /2)-2 tan<2> (θ1 /2))/ωZ0 are connected between the middle point of the distribution constant line and GND. The length of transmission lines 7 and 8 is a length corresponding to a phase angle θ2 =2tan<-1> (Z0 /Z1 ) at the using frequency, the distribution constant line of impedance Z2 =Z1 =Z0 /2<1/2> .tan(θ1 /2) is set, and the capacitances 11 and 12 of a capacitor C2 =(1/cos<2> (θ2 /2)-2tan<2> (θ2 /2))/ωZ0 are connected between the middle point of the distribution constant line and GND.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 90.degree. Hybrid circuit which is widely used as a basic circuit for distributing and synthesizing signals in communication equipment and the like, and also as a basic circuit for a balanced modulation / demodulation circuit, a mixer, a phase shifter and the like.

[0002]

2. Description of the Related Art A 90 ° hybrid circuit which distributes input power in the microwave band to output powers having the same amplitude and different phases from each other by 90 ° and outputs the resulting power is well known in the related art. FIG. 3 shows a conventional 90 ° hybrid circuit. FIG.
, 1, 2, 3, and 4 are first, second, third, and fourth ports, respectively, and 5a, 6a, 7a, and 8a are transmission lines. The first port 1 is used as an input port,
The second port 2 is used as the first output port and the third port
Port 3 is used as a second output port, and the fourth port 4 is used as an isolation port.

[0003] The conventional 90 ° hybrid circuit is designed to prevent reflection at each port when a load having impedance Z ₀ is connected to each of the first to fourth ports.
Transmission line 5a from input port 1 to first output port 2
And the impedance of the transmission line 6a from the second output port 3 to the isolation port 4 is set to be Z ₀ / √2, and the transmission line 7a from the input port 1 to the isolation port 4 and the first output port 2 the impedance of the transmission line 8a to the second output port 3 as well as set to be Z ₀ from, and a length corresponding to the phase angle theta = 90 ° in the frequency using the length of each transmission line 5a~8a .

In the above configuration, the input port 1
Is output from the first output port 2 and the second output port 3, and propagates from the input port 1 to the first output port 2 and from the input port 1 to the second output port 3. And a phase difference of 90 ° is generated between them. In addition, the isolation port 4 above the input port 1
There is a phase difference of 180 ° between the path going to the input port 1 and the path going down from the input port 1 to the isolation port 4. Is kept. The power input to the input port 1 in this manner is distributed to the first output port 2 and the second output port 3, and outputs having the same amplitude and a phase difference of 90 ° from each other.

[0005]

The conventional 90 ° hybrid circuit is constructed and operates as described above. However, as shown in FIG.
Since a length corresponding to 0 ° is required, and the size of the entire circuit is uniquely determined by the frequency and the substrate material, the circuit cannot be downsized. Further, since the impedance of the transmission line 5a and the transmission line 6a is different from the impedance of the transmission line 7a and the transmission line 8a, discontinuity of the distributed constant line occurs, and it takes time to analyze the discontinuity at the time of circuit design. There was a point.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the transmission line length is shortened to reduce the size of the circuit, and the discontinuity of the line due to the difference in the impedance of each transmission line is eliminated. It is an object of the present invention to provide a 90 ° hybrid circuit that does not require analysis of a discontinuous portion.

[0007]

Means for Solving the Problems] 90 ° hybrid circuit of the present invention, when the load connected to the first to fourth ports of the impedance Z _0, the transmission from the first port to the second port The length of the line and the length of the transmission line from the third port to the fourth port is set to a desired length (however, a length corresponding to the phase angle θ ₁ at the operating frequency, 0
<Θ ₁ ≦ 90 °), impedance Z ₁ = Z ₀ / √2 ·
as a distributed constant line of tan (θ _1/2), to connect the capacitance of the capacitive C ₁ between the midpoint and the GND of the distributed constant _{line, {C 1 = √2 · (} 1 / cos 2 (θ 1 / 2) -2tan ² (θ ₁
/ 2)) / ωZ ₀を The transmission line from the first port to the fourth port and the transmission line from the second port to the third port have a length corresponding to the phase angle θ ₂ at the working frequency. And set {θ ₂ = ₂ tan ^-1 (Z ₀ / Z ₁ )} impedance Z ₂ = Z ₁ = Z ₀ / √2 · tan (θ ₁ /
As a distributed constant line 2), and wherein the configuration of connecting the capacitance of the capacitive C ₂ between the midpoint and the GND of the distributed constant line. _{{C 2 = (1 / cos} 2 (θ 2/2) -2tan 2 (θ 2 /
2)) / ωZ ₀ ｝ Accordingly, by setting the above θ ₁ to a phase angle smaller than 90 °, the transmission line length can be reduced and the size can be reduced as compared with the conventional circuit, and the discontinuous portion of the distributed constant line can be reduced. This eliminates the need to analyze discontinuous parts during circuit design.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining the principle of the present invention. In FIG. 1, the same reference numerals as those in FIG. 3 denote the same or corresponding parts, and 5 to 8 denote the conventional circuits 5a to 5a shown in FIG.
A transmission line corresponding to 8a, and 9 to 12 indicate capacitance. A first port 1 is used as an input port, a second port 2 is used as a first output port, a third port 3 is used as a second output port, and a fourth port 4 is used as an isolation port. used.

The impedance of the transmission line 5 from the input port 1 to the first output port 2 and the impedance of the transmission line 6 from the second output port 3 to the isolation port 4 are Z
₁ , the length of these lines is used as the phase angle θ at the operating frequency.
_{It is} assumed that the length is equivalent to ₁ (0 <θ ₁ ≦ 90 °), and the capacitance of the capacitances 9 and 10 connected between the midpoint of each of the transmission lines 5 and 6 and GND is C ₁ . The impedance of the transmission line 7 from the input port 1 to the isolation port 4 and the impedance of the transmission line 8 from the first output port 2 to the second output port 3 are Z ₂ , respectively, and the length of these lines is the phase angle at the operating frequency. a length corresponding to theta _2, the capacitance of the capacitor 11 and 12 is connected between the midpoint and the GND of the transmission lines 7 and 8 are assumed to be C _2, these Z _1, Z _2, C ₁ , C ₂ , θ ₁ , θ
₂ is set to satisfy the following equation.

That is, the conventional transmission line 5a shown in FIG.
The F matrix of the transmission line 6a and the transmission line 5a to which the capacitance 9 of the present embodiment shown in FIG.
Since the F matrix of the transmission line 6 to which the capacitance and the capacitance 10 are connected can be expressed by Expression (2), Expressions (1) and (2) must be equal to make them equivalent. By solving this for Z ₁ and C ₁ , the following equations (3) and (4) are obtained.

[0011]

(Equation 1)

The transmission line 7a and the transmission line 8a
In order for the transmission line 7 to which the capacitance 11 is connected and the transmission line 8 to which the capacitance 12 is connected to be equivalent, Z ₂ and C ₂ are expressed by the following equations (5) and (6). Further, in order to eliminate the discontinuity between the lines, it is only necessary to make the impedances of the lines equal. Therefore, if Z ₁ = Z ₂ , the following equation (7) is obtained.

[0013]

(Equation 2)

That is, the length of the transmission line 5 and the length of the transmission line 6 are set to an arbitrary phase angle θ ₁ (where 0
<When a length corresponding to θ ₁ ≦ 90 °), since the impedance _{Z 1 = Z 0 / √2 ·} tan (θ 1/2) of the distributed constant lines, the midpoint and the GND of the distributed constant line during the capacitance _{C 1 = √2 · (1 /} cos 2 (θ 1/2) -2tan 2
_{(Θ 1/2)) /} ωZ connecting capacitance 9,10 _0. The lengths of the transmission lines 7 and 8 are equivalent to the phase angle θ ₂ = ₂ tan ^-1 (Z ₀ / Z ₁ ) at the operating frequency, and the impedance Z ₂ = Z ₁ = Z ₀ / √.
As _{2 · tan (θ 1/2} ) of the distributed constant line, between the middle point and the GND of the distributed constant line, the capacitance C ^₂ = (1 / cos _{2
^{(Θ 2/2) -2tan 2}} (θ 2/2)) / ωZ 0 of In the structure for connecting the capacitance 11 and 12, the phase angle 90 in the line length using frequency as in the conventional circuit
The length can be shortened without being limited to the length corresponding to °, whereby the size of the circuit can be reduced. Further, since the impedance of each line can be made equal, discontinuity between the lines is eliminated, and an efficient design that does not require analysis of the discontinuous portion can be performed.

FIG. 2 shows an embodiment of a 90 ° hybrid circuit according to the present invention. The use frequency 6GH _Z, the transmission line 5
And Z ₁ , Z ₂ , C ₁ , when the transmission line 6 has a length corresponding to a phase angle of 45 ° at a working frequency of 6 GHz.
The values of C ₂ , θ ₁ and θ ₂ are shown. 4 to 7 correspond to FIG.
FIG. 4 is a diagram showing the calculation results of the circuit characteristics shown in FIG. 4 standardized by use frequency, FIG. 4 is a diagram showing reflection characteristics S11, S22, S33, and S44 of ports 1 to 4, and FIG. Transmission characteristics S21 between ports and between ports 1-3,
FIG. 6 is a diagram showing S31, and FIG.
FIG. 7 is a graph showing an isolation characteristic between the three ports.
FIG. 3 is a diagram showing phase characteristics between -2 and between ports 1-3. As is apparent from these figures, even if the circuit is downsized, a 90 ° hybrid circuit having sufficient performance in all of the reflection characteristics, transmission characteristics, isolation characteristics, and phase characteristics can be obtained.

[0016]

As described above, the 90 ° hybrid circuit of the present invention can reduce the size of the circuit by shortening the transmission line, and reduce the chip area especially when the circuit is constituted by the MMIC, thereby reducing the manufacturing cost. Reduction can be achieved. In addition, since the discontinuity of the transmission line is eliminated, there is an effect that the analysis work of the discontinuous portion at the time of design, which is conventionally required, becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a 90 ° hybrid circuit of the present invention.

FIG. 2 is a diagram showing one embodiment of the 90 ° hybrid circuit shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a conventional 90 ° hybrid circuit.

FIG. 4 is a diagram showing reflection characteristics of the 90 ° hybrid circuit shown in FIG. 2;

FIG. 5 is a diagram showing transmission characteristics of the 90 ° hybrid circuit shown in FIG. 2;

FIG. 6 is a diagram illustrating an isolation characteristic of the 90 ° hybrid circuit illustrated in FIG. 2;

FIG. 7 is a diagram showing phase characteristics of the 90 ° hybrid circuit shown in FIG. 2;

[Explanation of symbols]

 1 to 4, 1st, 2nd, 3rd and 4th ports respectively 5 to 8 transmission lines 9 to 12 capacitances

Claims (1)

[Claims] A first port serving as an input port, a second port serving as a first output port, a third port serving as a second output port, and a fourth port serving as an isolation port; From the port and the second output port,
In a 90 ° hybrid circuit configured to obtain outputs having the same amplitude and a phase different from each other by 90 °, when a load connected to each of the first to fourth ports has an impedance Z ₀ , The lengths of the transmission lines from the third port to the second port and the transmission lines from the third port to the fourth port are set to desired lengths (provided that the phase angle θ _{1 at the} operating frequency is used).
Corresponds to a _{length, 0 <θ 1 ≦ 90 °} ), as a distributed constant line impedance _{Z 1 = Z 0 / √2 ·} tan (θ 1/2), the midpoint and the GND of the distributed constant line connect the capacitance of the capacitive C _{1 between, {C 1 = √2 · (} 1 / cos 2 (θ 1/2) -2tan 2 (θ 1
/ 2)) / ωZ ₀を The transmission line from the first port to the fourth port and the transmission line from the second port to the third port have a length corresponding to the phase angle θ ₂ at the working frequency. And set {θ ₂ = ₂ tan ^-1 (Z ₀ / Z ₁ )} impedance Z ₂ = Z ₁ = Z ₀ / √2 · tan (θ ₁ /
As the distributed constant line of 2), a capacitance of a capacitance C ₂ is connected between the midpoint of the distributed constant line and GND.
_{{C 2 = (1 / cos} 2 (θ 2/2) -2tan 2 (θ 2 /
2)) A 90 ° hybrid circuit characterized by the / ωZ ₀構成 configuration.